Ignition "OFF"

Connect Scantool and Ignition "ON".

Monitor the HO2S parameters and signal waveform on scantool.

Are the signal of rear HO2S and waveform the same as that of the front HO2S?

YES

▶ Go to "System Inspection" procedure.

NO

▶ Fault is intermittent caused by poor contact in the sensor’s and/or PCM’s connector or was repairedand PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection,bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and goto "Verification vehicle Repair" procedure.